/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.
Copyright (C) 2000-2006 Tim Angus

This file is part of Tremulous.

Tremulous is free software; you can redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.

Tremulous is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Tremulous; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/

// cg_predict.c -- this file generates cg.predictedPlayerState by either
// interpolating between snapshots from the server or locally predicting
// ahead the client's movement.
// It also handles local physics interaction, like fragments bouncing off walls


#include "cg_local.h"

static pmove_t  cg_pmove;

static int      cg_numSolidEntities;
static centity_t *cg_solidEntities[MAX_ENTITIES_IN_SNAPSHOT];
static int      cg_numTriggerEntities;
static centity_t *cg_triggerEntities[MAX_ENTITIES_IN_SNAPSHOT];

/*
====================
CG_BuildSolidList

When a new cg.snap has been set, this function builds a sublist
of the entities that are actually solid, to make for more
efficient collision detection
====================
*/
void CG_BuildSolidList(void)
{
	int             i;
	centity_t      *cent;
	snapshot_t     *snap;
	entityState_t  *ent;

	cg_numSolidEntities = 0;
	cg_numTriggerEntities = 0;

	if(cg.nextSnap && !cg.nextFrameTeleport && !cg.thisFrameTeleport)
		snap = cg.nextSnap;
	else
		snap = cg.snap;

	for(i = 0; i < snap->numEntities; i++)
	{
		cent = &cg_entities[snap->entities[i].number];
		ent = &cent->currentState;

		if(ent->eType == ET_ITEM || ent->eType == ET_PUSH_TRIGGER || ent->eType == ET_TELEPORT_TRIGGER)
		{
			cg_triggerEntities[cg_numTriggerEntities] = cent;
			cg_numTriggerEntities++;
			continue;
		}

		if(cent->nextState.solid && ent->eType != ET_MISSILE)
		{
			cg_solidEntities[cg_numSolidEntities] = cent;
			cg_numSolidEntities++;
			continue;
		}
	}
}

/*
====================
CG_ClipMoveToEntities

====================
*/
static void CG_ClipMoveToEntities(const vec3_t start, const vec3_t mins,
								  const vec3_t maxs, const vec3_t end, int skipNumber,
								  int mask, trace_t * tr, traceType_t collisionType)
{
	int             i, j, x, zd, zu;
	trace_t         trace;
	entityState_t  *ent;
	clipHandle_t    cmodel;
	vec3_t          bmins, bmaxs;
	vec3_t          origin, angles;
	centity_t      *cent;

	//SUPAR HACK
	//this causes a trace to collide with the local player
	if(skipNumber == MAGIC_TRACE_HACK)
		j = cg_numSolidEntities + 1;
	else
		j = cg_numSolidEntities;

	for(i = 0; i < j; i++)
	{
		if(i < cg_numSolidEntities)
			cent = cg_solidEntities[i];
		else
			cent = &cg.predictedPlayerEntity;

		ent = &cent->currentState;

		if(ent->number == skipNumber)
			continue;

		if(ent->solid == SOLID_BMODEL)
		{
			// special value for bmodel
			cmodel = trap_CM_InlineModel(ent->modelindex);
			VectorCopy(cent->lerpAngles, angles);
			BG_EvaluateTrajectory(&cent->currentState.pos, cg.physicsTime, origin);
		}
		else
		{
			// encoded bbox
			x = (ent->solid & 255);
			zd = ((ent->solid >> 8) & 255);
			zu = ((ent->solid >> 16) & 255) - 32;

			bmins[0] = bmins[1] = -x;
			bmaxs[0] = bmaxs[1] = x;
			bmins[2] = -zd;
			bmaxs[2] = zu;

			if(i == cg_numSolidEntities)
				BG_FindBBoxForClass((ent->powerups >> 8) & 0xFF, bmins, bmaxs, NULL, NULL, NULL);

			cmodel = trap_CM_TempBoxModel(bmins, bmaxs);
			VectorCopy(vec3_origin, angles);
			VectorCopy(cent->lerpOrigin, origin);
		}


		if(collisionType == TT_CAPSULE)
		{
			trap_CM_TransformedCapsuleTrace(&trace, start, end, mins, maxs, cmodel, mask, origin, angles);
		}
		else if(collisionType == TT_AABB)
		{
			trap_CM_TransformedBoxTrace(&trace, start, end, mins, maxs, cmodel, mask, origin, angles);
		}
		else if(collisionType == TT_BISPHERE)
		{
			trap_CM_TransformedBiSphereTrace(&trace, start, end, mins[0], maxs[0], cmodel, mask, origin);
		}

		if(trace.allsolid || trace.fraction < tr->fraction)
		{
			trace.entityNum = ent->number;

			if(tr->lateralFraction < trace.lateralFraction)
			{
				float           oldLateralFraction = tr->lateralFraction;

				*tr = trace;
				tr->lateralFraction = oldLateralFraction;
			}
			else
				*tr = trace;
		}
		else if(trace.startsolid)
			tr->startsolid = qtrue;

		if(tr->allsolid)
			return;
	}
}

/*
================
CG_Trace
================
*/
void CG_Trace(trace_t * result, const vec3_t start, const vec3_t mins, const vec3_t maxs, const vec3_t end,
			  int skipNumber, int mask)
{
	trace_t         t;

	trap_CM_BoxTrace(&t, start, end, mins, maxs, 0, mask);
	t.entityNum = t.fraction != 1.0 ? ENTITYNUM_WORLD : ENTITYNUM_NONE;
	// check all other solid models
	CG_ClipMoveToEntities(start, mins, maxs, end, skipNumber, mask, &t, TT_AABB);

	*result = t;
}

/*
================
CG_CapTrace
================
*/
void CG_CapTrace(trace_t * result, const vec3_t start, const vec3_t mins, const vec3_t maxs, const vec3_t end,
				 int skipNumber, int mask)
{
	trace_t         t;

	trap_CM_CapsuleTrace(&t, start, end, mins, maxs, 0, mask);
	t.entityNum = t.fraction != 1.0 ? ENTITYNUM_WORLD : ENTITYNUM_NONE;
	// check all other solid models
	CG_ClipMoveToEntities(start, mins, maxs, end, skipNumber, mask, &t, TT_CAPSULE);

	*result = t;
}

/*
================
CG_BiSphereTrace
================
*/
void CG_BiSphereTrace(trace_t * result, const vec3_t start, const vec3_t end,
					  const float startRadius, const float endRadius, int skipNumber, int mask)
{
	trace_t         t;
	vec3_t          mins, maxs;

	mins[0] = startRadius;
	maxs[0] = endRadius;

	trap_CM_BiSphereTrace(&t, start, end, startRadius, endRadius, 0, mask);
	t.entityNum = t.fraction != 1.0 ? ENTITYNUM_WORLD : ENTITYNUM_NONE;
	// check all other solid models
	CG_ClipMoveToEntities(start, mins, maxs, end, skipNumber, mask, &t, TT_BISPHERE);

	*result = t;
}

/*
================
CG_PointContents
================
*/
int CG_PointContents(const vec3_t point, int passEntityNum)
{
	int             i;
	entityState_t  *ent;
	centity_t      *cent;
	clipHandle_t    cmodel;
	int             contents;

	contents = trap_CM_PointContents(point, 0);

	for(i = 0; i < cg_numSolidEntities; i++)
	{
		cent = cg_solidEntities[i];

		ent = &cent->currentState;

		if(ent->number == passEntityNum)
			continue;

		if(ent->solid != SOLID_BMODEL)	// special value for bmodel
			continue;

		cmodel = trap_CM_InlineModel(ent->modelindex);

		if(!cmodel)
			continue;

		contents |= trap_CM_TransformedPointContents(point, cmodel, ent->origin, ent->angles);
	}

	return contents;
}


/*
========================
CG_InterpolatePlayerState

Generates cg.predictedPlayerState by interpolating between
cg.snap->player_state and cg.nextFrame->player_state
========================
*/
static void CG_InterpolatePlayerState(qboolean grabAngles)
{
	float           f;
	int             i;
	playerState_t  *out;
	snapshot_t     *prev, *next;

	out = &cg.predictedPlayerState;
	prev = cg.snap;
	next = cg.nextSnap;

	*out = cg.snap->ps;

	// if we are still allowing local input, short circuit the view angles
	if(grabAngles)
	{
		usercmd_t       cmd;
		int             cmdNum;

		cmdNum = trap_GetCurrentCmdNumber();
		trap_GetUserCmd(cmdNum, &cmd);

		PM_UpdateViewAngles(out, &cmd);
	}

	// if the next frame is a teleport, we can't lerp to it
	if(cg.nextFrameTeleport)
		return;

	if(!next || next->serverTime <= prev->serverTime)
		return;

	f = (float)(cg.time - prev->serverTime) / (next->serverTime - prev->serverTime);

	i = next->ps.bobCycle;
	if(i < prev->ps.bobCycle)
		i += 256;				// handle wraparound

	out->bobCycle = prev->ps.bobCycle + f * (i - prev->ps.bobCycle);

	for(i = 0; i < 3; i++)
	{
		out->origin[i] = prev->ps.origin[i] + f * (next->ps.origin[i] - prev->ps.origin[i]);

		if(!grabAngles)
			out->viewangles[i] = LerpAngle(prev->ps.viewangles[i], next->ps.viewangles[i], f);

		out->velocity[i] = prev->ps.velocity[i] + f * (next->ps.velocity[i] - prev->ps.velocity[i]);
	}
}


/*
=========================
CG_TouchTriggerPrediction

Predict push triggers and items
=========================
*/
static void CG_TouchTriggerPrediction(void)
{
	int             i;
	trace_t         trace;
	entityState_t  *ent;
	clipHandle_t    cmodel;
	centity_t      *cent;
	qboolean        spectator;

	// dead clients don't activate triggers
	if(cg.predictedPlayerState.stats[STAT_HEALTH] <= 0)
		return;

	spectator = (cg.predictedPlayerState.pm_type == PM_SPECTATOR);

	if(cg.predictedPlayerState.pm_type != PM_NORMAL && !spectator)
		return;

	for(i = 0; i < cg_numTriggerEntities; i++)
	{
		cent = cg_triggerEntities[i];
		ent = &cent->currentState;

		if(ent->solid != SOLID_BMODEL)
			continue;

		cmodel = trap_CM_InlineModel(ent->modelindex);
		if(!cmodel)
			continue;

		trap_CM_BoxTrace(&trace, cg.predictedPlayerState.origin, cg.predictedPlayerState.origin,
						 cg_pmove.mins, cg_pmove.maxs, cmodel, -1);

		if(!trace.startsolid)
			continue;

		if(ent->eType == ET_TELEPORT_TRIGGER)
			cg.hyperspace = qtrue;
	}

	// if we didn't touch a jump pad this pmove frame
	if(cg.predictedPlayerState.jumppad_frame != cg.predictedPlayerState.pmove_framecount)
	{
		cg.predictedPlayerState.jumppad_frame = 0;
		cg.predictedPlayerState.jumppad_ent = 0;
	}
}



/*
=================
CG_PredictPlayerState

Generates cg.predictedPlayerState for the current cg.time
cg.predictedPlayerState is guaranteed to be valid after exiting.

For demo playback, this will be an interpolation between two valid
playerState_t.

For normal gameplay, it will be the result of predicted usercmd_t on
top of the most recent playerState_t received from the server.

Each new snapshot will usually have one or more new usercmd over the last,
but we simulate all unacknowledged commands each time, not just the new ones.
This means that on an internet connection, quite a few pmoves may be issued
each frame.

OPTIMIZE: don't re-simulate unless the newly arrived snapshot playerState_t
differs from the predicted one.  Would require saving all intermediate
playerState_t during prediction.

We detect prediction errors and allow them to be decayed off over several frames
to ease the jerk.
=================
*/
void CG_PredictPlayerState(void)
{
	int             cmdNum, current, i;
	playerState_t   oldPlayerState;
	qboolean        moved;
	usercmd_t       oldestCmd;
	usercmd_t       latestCmd;

	cg.hyperspace = qfalse;		// will be set if touching a trigger_teleport

	// if this is the first frame we must guarantee
	// predictedPlayerState is valid even if there is some
	// other error condition
	if(!cg.validPPS)
	{
		cg.validPPS = qtrue;
		cg.predictedPlayerState = cg.snap->ps;
	}


	// demo playback just copies the moves
	if(cg.demoPlayback || (cg.snap->ps.pm_flags & PMF_FOLLOW))
	{
		CG_InterpolatePlayerState(qfalse);
		return;
	}

	// non-predicting local movement will grab the latest angles
	if(cg_nopredict.integer || cg_synchronousClients.integer)
	{
		CG_InterpolatePlayerState(qtrue);
		return;
	}

	// prepare for pmove
	cg_pmove.ps = &cg.predictedPlayerState;
	cg_pmove.trace = CG_Trace;
	cg_pmove.pointcontents = CG_PointContents;
	cg_pmove.debugLevel = cg_debugMove.integer;

	if(cg_pmove.ps->pm_type == PM_DEAD)
		cg_pmove.tracemask = MASK_PLAYERSOLID & ~CONTENTS_BODY;
	else
		cg_pmove.tracemask = MASK_PLAYERSOLID;

	if(cg.snap->ps.persistant[PERS_TEAM] == TEAM_SPECTATOR)
		cg_pmove.tracemask &= ~CONTENTS_BODY;	// spectators can fly through bodies

	cg_pmove.noFootsteps = 0;

	// save the state before the pmove so we can detect transitions
	oldPlayerState = cg.predictedPlayerState;

	current = trap_GetCurrentCmdNumber();

	// if we don't have the commands right after the snapshot, we
	// can't accurately predict a current position, so just freeze at
	// the last good position we had
	cmdNum = current - CMD_BACKUP + 1;
	trap_GetUserCmd(cmdNum, &oldestCmd);

	if(oldestCmd.serverTime > cg.snap->ps.commandTime && oldestCmd.serverTime < cg.time)
	{							// special check for map_restart
		if(cg_showmiss.integer)
			CG_Printf("exceeded PACKET_BACKUP on commands\n");

		return;
	}

	// get the latest command so we can know which commands are from previous map_restarts
	trap_GetUserCmd(current, &latestCmd);

	// get the most recent information we have, even if
	// the server time is beyond our current cg.time,
	// because predicted player positions are going to
	// be ahead of everything else anyway
	if(cg.nextSnap && !cg.nextFrameTeleport && !cg.thisFrameTeleport)
	{
		cg.predictedPlayerState = cg.nextSnap->ps;
		cg.physicsTime = cg.nextSnap->serverTime;
	}
	else
	{
		cg.predictedPlayerState = cg.snap->ps;
		cg.physicsTime = cg.snap->serverTime;
	}

	if(pmove_msec.integer < 8)
		trap_Cvar_Set("pmove_msec", "8");
	else if(pmove_msec.integer > 33)
		trap_Cvar_Set("pmove_msec", "33");

	cg_pmove.pmove_fixed = pmove_fixed.integer;	// | cg_pmove_fixed.integer;
	cg_pmove.pmove_msec = pmove_msec.integer;

	// run cmds
	moved = qfalse;

	for(cmdNum = current - CMD_BACKUP + 1; cmdNum <= current; cmdNum++)
	{
		// get the command
		trap_GetUserCmd(cmdNum, &cg_pmove.cmd);

		if(cg_pmove.pmove_fixed)
			PM_UpdateViewAngles(cg_pmove.ps, &cg_pmove.cmd);

		// don't do anything if the time is before the snapshot player time
		if(cg_pmove.cmd.serverTime <= cg.predictedPlayerState.commandTime)
			continue;

		// don't do anything if the command was from a previous map_restart
		if(cg_pmove.cmd.serverTime > latestCmd.serverTime)
			continue;

		// check for a prediction error from last frame
		// on a lan, this will often be the exact value
		// from the snapshot, but on a wan we will have
		// to predict several commands to get to the point
		// we want to compare
		if(cg.predictedPlayerState.commandTime == oldPlayerState.commandTime)
		{
			vec3_t          delta;
			float           len;

			if(cg.thisFrameTeleport)
			{
				// a teleport will not cause an error decay
				VectorClear(cg.predictedError);

				if(cg_showmiss.integer)
					CG_Printf("PredictionTeleport\n");

				cg.thisFrameTeleport = qfalse;
			}
			else
			{
				vec3_t          adjusted;

				CG_AdjustPositionForMover(cg.predictedPlayerState.origin,
										  cg.predictedPlayerState.groundEntityNum, cg.physicsTime, cg.oldTime, adjusted);

				if(cg_showmiss.integer)
				{
					if(!VectorCompare(oldPlayerState.origin, adjusted))
						CG_Printf("prediction error\n");
				}

				VectorSubtract(oldPlayerState.origin, adjusted, delta);
				len = VectorLength(delta);

				if(len > 0.1)
				{
					if(cg_showmiss.integer)
						CG_Printf("Prediction miss: %f\n", len);

					if(cg_errorDecay.integer)
					{
						int             t;
						float           f;

						t = cg.time - cg.predictedErrorTime;
						f = (cg_errorDecay.value - t) / cg_errorDecay.value;

						if(f < 0)
							f = 0;

						if(f > 0 && cg_showmiss.integer)
							CG_Printf("Double prediction decay: %f\n", f);

						VectorScale(cg.predictedError, f, cg.predictedError);
					}
					else
						VectorClear(cg.predictedError);

					VectorAdd(delta, cg.predictedError, cg.predictedError);
					cg.predictedErrorTime = cg.oldTime;
				}
			}
		}

		// don't predict gauntlet firing, which is only supposed to happen
		// when it actually inflicts damage
		for(i = WP_NONE + 1; i < WP_NUM_WEAPONS; i++)
			cg_pmove.autoWeaponHit[i] = qfalse;

		if(cg_pmove.pmove_fixed)
			cg_pmove.cmd.serverTime = ((cg_pmove.cmd.serverTime + pmove_msec.integer - 1) /
									   pmove_msec.integer) * pmove_msec.integer;

		Pmove(&cg_pmove);

		moved = qtrue;

		// add push trigger movement effects
		CG_TouchTriggerPrediction();

		// check for predictable events that changed from previous predictions
		//CG_CheckChangedPredictableEvents(&cg.predictedPlayerState);
	}

	if(cg_showmiss.integer > 1)
		CG_Printf("[%i : %i] ", cg_pmove.cmd.serverTime, cg.time);

	if(!moved)
	{
		if(cg_showmiss.integer)
			CG_Printf("not moved\n");

		return;
	}

	// adjust for the movement of the groundentity
	CG_AdjustPositionForMover(cg.predictedPlayerState.origin,
							  cg.predictedPlayerState.groundEntityNum, cg.physicsTime, cg.time, cg.predictedPlayerState.origin);

	if(cg_showmiss.integer)
	{
		if(cg.predictedPlayerState.eventSequence > oldPlayerState.eventSequence + MAX_PS_EVENTS)
			CG_Printf("WARNING: dropped event\n");
	}

	// fire events and other transition triggered things
	CG_TransitionPlayerState(&cg.predictedPlayerState, &oldPlayerState);

	if(cg_showmiss.integer)
	{
		if(cg.eventSequence > cg.predictedPlayerState.eventSequence)
		{
			CG_Printf("WARNING: double event\n");
			cg.eventSequence = cg.predictedPlayerState.eventSequence;
		}
	}
}
